The present invention relates to a laser imaging apparatus, which forms an image on a surface using a scanning laser beam.
Conventionally, a laser imaging apparatus such as a direct imager or a laser photo-plotter is used for forming a circuit pattern on a substrate for a printed-circuit board or a semiconductor element. In such a laser imaging apparatus, a laser beam emitted by a laser source is deflected by a polygonal mirror so that the defected beam scans on a surface on which photo-resistive material is provided. During the scanning operation, the laser beam is modulated in accordance with an image to be formed on the surface. Further, the surface exposed to the scanning beam is moved in a direction perpendicular to the scanning line. Thus, a two-dimensional image is formed on the surface.
Recently, there is a need for a laser imaging apparatus which is capable of forming an image on a surface wider in size. In order to form a wide image, it is necessary to widen an effective scanning range of the scanning optical system. For this purpose, an optical system of the laser imaging apparatus, i.e., the polygonal mirror and an imaging optical system may be made large in size. However, in such a configuration, image formation density is lowered (i.e., density of pixels consisting of an image is lowered).
For avoiding such defects, an imaging apparatus provided with a plurality of scanning optical systems has been suggested. Specifically, the plurality of optical systems are arranged along the scanning direction, and a surface to be scanned is divided into a plurality of areas along the scanning direction, which are scanned by the plurality of scanning optical systems, respectively. The adjoining image segments formed by adjoining scanning systems are generally connected seamlessly. With this configuration, a wide image can be formed with maintaining the high density.
Another need is a xe2x80x9cmultiple imagingxe2x80x9d or to form a plurality of relatively small images on a wide circuit board using the imaging apparatus having a plurality of scanning systems. In this case, each of the plurality of scanning systems is used for forming the smaller image so that the plurality of images are formed on the wide circuit board. This course of manufacturing process enables the obtaining of a large amount of circuit boards respectively corresponding to the smaller images in a relatively short period of time.
When such a xe2x80x9cmultiple imagingxe2x80x9d is performed, it is important that a clearance should be provided between the adjoining images, since the circuit board is to be cut at the clearance later to form smaller boards respectively having the plurality of images. Therefore, when the multiple imaging is performed, the effective scanning range of each scanning system is not fully used since the images should be separated with a certain clearance formed therebetween.
It is therefore an object of the invention to provide an improved laser imaging apparatus, which has a plurality of scanning systems aligned in a main scanning direction, capable of forming a seamless large image using the plurality of scanning systems, and of forming small images, with a clearance therebetween, using the entire effective scanning ranges of the plurality of scanning systems.
For the above object, there is provided a laser imaging apparatus for forming an image on a surface of a substrate, which is provided with a laser source unit that emits a plurality of laser beams, a table mounting the substrate, the table being movable in a first direction within a predetermined plane, a plurality of scanning optical systems which receive and deflect the plurality of laser beams emitted by the laser source unit to form scanning beam spots on the surface, respectively, the scanning beam spots scanning in a second direction that is perpendicular to the first direction, and a mechanism that moves the at least one of the plurality of scanning optical systems in the second direction.
According to this configuration, by adjusting the location of the scanning system in the second direction, the object can easily be achieved.
Optionally, each of the plurality of scanning optical systems has an effective scanning range defined along the second direction, and the laser imaging apparatus further includes a controller. When a plurality of image patterns, each of which has a width, in the second direction, not greater than the effective scanning range are to be formed, the controller controls the plurality of scanning optical systems to form the plurality of image patterns, respectively, and the controller may further control the mechanism to locate the at least one of the plurality of scanning optical systems at a position where the plurality of image patterns respectively formed by the plurality of scanning optical systems are separated from each other by a predetermined amount.
Optionally or alternatively, when an image pattern whose width, in the second direction, is greater than the effective scanning range is to be formed, the controller divides the.image pattern into a plurality of image segments in accordance with the number of the plurality of scanning optical systems, the controller further controlling the mechanism to locate the at least one of the plurality of scanning optical systems at a position where the image segments respectively formed by the plurality of scanning optical systems are connected to form the image pattern.
In a particular case, the widths of the plurality of image segments may be substantially the same.
Optionally, a central portion of each of the plurality of scanning optical systems is located at the center of the width of each of the image segments when they are formed.
In a particular case, the plurality of scanning optical systems consist of two scanning optical systems.
In this case, only one of the two scanning optical systems may be driven by the mechanism to move in the second direction.
According to another aspect of the invention, there is provided a laser imaging apparatus for forming an image on a surface of a substrate, which is provided with a laser source that emits a laser beam, a table mounting the substrate, the table being movable in a first direction within a predetermined plane, a scanning optical system which receives and deflects the laser beam emitted by the laser source to form a scanning beam spot on the substrate, the scanning beam spot scanning in a second direction that is perpendicular to the first direction, and a mechanism that moves the scanning optical system in the second direction.
Optionally, the scanning optical system has an effective scanning range defined in the second direction, and the laser imaging apparatus may further include a controller. When a plurality of image patterns, each of which has a width, in the second direction, not greater than the effective scanning range, are to be formed the controller controls the scanning optical system to form the plurality of image patterns, sequentially, and the controller may further control the mechanism to move the scanning optical system such that the plurality of image patterns sequentially formed by the scanning optical system are separated from each other by a predetermined amount.
Optionally or alternatively, when an image pattern whose width, in the second direction, is greater than the effective scanning range is to be formed, the controller divides the image pattern into a plurality of image segments, and the controller may further control the mechanism such that the plurality of image segments are formed sequentially, the plurality of image segments sequentially formed by the scanning optical system are seamlessly connected to form the image pattern.
Optionally, a central portion of the scanning optical system is located at the center of the width of each of the image segments when each of the image segments is formed.
In a particular case, a central portion of the effective scanning range of the scanning optical system is located at the center of the width of each of the image patterns when each of the image patterns is formed.
Still optionally, the image segments may have substantially the same widths.